This invention relates to an apparatus for processing photographic material. In particular the invention relates to a method of reducing the volume of low volume processors.
The processing of photosensitive material such as photographic film involves a series of steps such as developing, bleaching, fixing, washing and drying. In this process a continuous web of film or cut sheet of film is sequentially conveyed through a series of stations or tanks, with each one containing a different processing solution appropriate to the process step at that stage.
A large photofinishing apparatus utilises rack and tank configurations that contain approximately 100 liters of each processing solution. A smaller photofinishing apparatus such as a minilab may have tanks which contain less than 10 liters of processing solution. However these tanks have generally been replaced by low volume thin tanks in which the material to be processed passes through a narrow processing channel. Such a processing apparatus is disclosed in, for example, U.S. Pat. No. 5,420,658. This document discloses a low volume photographic material processing apparatus that utilises a narrow substantially horizontal processing channel. The channel has an upturned entrance and exit to contain the processing solution within the channel. The processing apparatus will contain a smaller volume of processing solution than was previously used in regular sized processing tanks.
However it is desirable to still further reduce the volume of the entire processing unit, including the circulation system for transferring solution from a reservoir to the processing channel and back again. This reduces the energy input to heat the solution and the time required for the processing.
It is an aim of the invention to reduce the volume of a processing unit. This has been done by removing the filter from the main circulation lines.
According to the present invention there is provided an apparatus for processing photographic material comprising a processing chamber through which the material to be processed passes, said chamber having an inlet for processing solution and an outlet for processing solution, a circulation system connecting the inlet and the outlet outside of the chamber, a buffer reservoir of processing solution for supplying processing solution to the circulation system and means for circulating the processing solution through the chamber and circulation system, filter means for filtering the processing solution being located external to the circulation system such that the solution is filtered only on entry to or exit from the circulation system.
Preferably the filter is located within the reservoir.
The invention further provides a method of processing photographic material comprising the steps of providing a processing chamber and associated circulation system with a small volume of processing solution from a reservoir of processing solution, passing the photographic material through the processing chamber, circulating the processing solution through the chamber and the system, and returning the solution to the reservoir, the processing solution being filtered as it is provided to the circulation system and/or on exit therefrom.
The apparatus of the invention allows simple flush cleaning of the processing chamber. This reduces contamination of the processing chamber by previously used solutions. The solution may be cleaned before processing or after processing depending on the position of the filter within the system. If the filter is located within the solution supply cartridge particles will settle to the bottom, extending the life of the filter. Such an embodiment also reduces the maintenance required. Furthermore, the operator never has to handle a wet filter. The apparatus saves energy by reducing the heating requirement.
The invention can be applied with advantage to multi-stage processes such as photographic processing including developing, fixing, bleaching, washing, etc.
The invention is applicable to any process for colour film, colour paper, reversal film, reversal paper, black and white film or paper.